Common neighbour analysis for binary atomic systems

The structure analysis of atom configurations obtained from molecular simulation is usually conducted by the radial pair correlation function. It describes the probability of finding an atom in a certain distance to a reference atom. By comparison with the radial pair correlation functions of perfectly ordered crystal structures one can often determine the structure type of a system. Difficulties arise when several crystal structures are present and partly ordered/disordered binary systems are investigated. In these cases the common neighbour analysis is useful. This is a powerful method for the determination of the different crystal structures and their fraction in atom configurations obtained from molecular simulations. Up to now this method has been developed and applied to monatomic systems. Here we describe an extension of the method to binary atomic systems and present signatures for bulk and the [1 0 0]-, [1 1 0]- and [1 1 1]-surfaces of four face centred binary structures. These are the L1 0 (AuCu), L1 1 (CuPt), L1 2 (Cu 3 Au) and L6 0 (CuTi 3 ) structures.